Preliminary Study of Using Colloidal SiO2@ZrO2 Particles in Recovering Actinides from Water and Immobilizing them in a Glass-Ceramic

Abstract

Actinides, which are toxic for humans, increased their presence in the hydrosphere over the last 80 years. Though actinide recovery from water and immobilization for safe storage is technically feasible, it remains a complex process. Herein, we preliminary studied SiO2@ZrO2 in recovering actinides from water and trapping them in a glass-ceramic upon thermal treatment. To simplify our experimental work, we surrogated radioactive actinides with stable cerium. In the first part of the work, we tested SiO2@ZrO2's ability to recover Ce from water in batch systems. Then, we thermally treated SiO2@ZrO2 with Ce to form a glass-ceramic. All batch experiments showed that SiO2@ZrO2 removes Ce from water. Moreover, all experiments show that SiO2@ZrO2 with Ce converts into a glass-ceramic upon thermal treatment. When heated up to 1000 °C, particles remained spherical, and Ce remained trapped within the structure of crystalline spheroids located between the outer surface and a 50 nm depth. When heated up to 1450 °C, sintering produced bigger particles than the original colloid, and Ce remained trapped within the structure of crystalline spheroids having a broad size distribution located everywhere in the particles.